Signor to siemens brothers



3 Sheets-Shet 1.

(No Model.)

J. S. RAWORTH.

ELECTRIC METER.

No. 338,549. Patented Mar.

(No Model.) 3 Sheets-Sheet 2' J. S. RAWORTH.

ELECTRIC METER.

No. 338,549. Patented Mar. 23, 1886.

bhwwabmus.

N. PETERS Phowhma u lwr, Wuhinglan. D C

(No Model.) 3 Sheets-Sheet 3.

J. S. RAWORTH.

ELEGTRIU METER.

Patented Mar. 23, 1886.

UNiTEn STATES PATENT OFFICE.

JOHN SMITH BAWVORTH, OF MANCHESTER, COUNTY OF LANCASTER, AS-

SIGNOB TO SIEMENS BROTHERS & COMPANY, (LIMITED,) OF 12 QUEEN ANNES GATE,TVESTMINSTER, COUNTY OF MIDDLESEX, ENGLAND.

ELECTRIC METER.

SPECIFICATION forming part of Letters Patent No 338,549. dated March23,1886.

Application filed February 25, 1885. Serial No. 157,027.

(No model.) Patented in Eng'and May 13. 1884, No. 7,668; in FranceFebruary 14, 1885, No. 167,046 in Germany February 15,1855, No. 33,950,and in Belgium February 17, 1585, No. 67,920.

To ctZZ whom it may concern.-

Be it known that I, J OHN SMITH RAwoR'rH, a citizen of England, residingat Manchester, in the county of Lancaster, England, have invented a newand useful Electric Meter, (for which I have obtained a patentin GreatBritain, dated May 13, 1884, No. 7,668,) of which the following is aspecification.

My invention relates to an electric meter that is to say, an instrumentfor measuring the electric current in a circuitin which case it maybetermed an electro-dynamometer, or with suitable modifications formeasuring the electro-motive force, in which case it may be called avolt-meter. For both purposes the principles of action are the same, butthe construction is so far modified as to suit two different conditions,the chief modification being in the character of the coils employed. Inthe one case, for the electrodynamometer a coilconductor of largesectional area and very low resistance is used. In the other case, forthe volt-meter coils of fine wire and very high resistance are used.

I will describe both forms, referring to the accompanying drawings, inthe several figures of which the same reference-letters are as much aspossible employed to indicate corresponding parts.

Figure 1 is avertical section, and Fig. 2 isa sectional plan, of anelectro-dynamometer according to my invention, Fig. 3 being a front viewshowing the parts immediately behind the dial, which is supposed to beremoved. Fig. 4 is a vertical section, and Fig. 5 a sectional plan, ofthe modified form of the instrument constituting a volt-meter, Fig. 6being a transverse section.

A is an iron spindle, delicately pivoted atits ends, where there are twoiron arms, a a, projecting from it in opposite directions. Around thespindle A there are conducting-coils B, consisting for theelectrodynamometer, as shown in Figs. 1 and 2, of a few convolutions ofcopper bar of rectangular section helically wound without contact witheach other; but in the volt-meter, as shown in Figs. 4 and 5, consistingof numerous convolutions of fine insulated wire. In either case, whenthese coils are acted on by electricity, the spindle A becomespolarized, its armsaa constituting polar extensions of the magnet intowhich it is converted. As shown in Fig. 2, the electric current enteringby the post 0 passes along a metallic framing, O C" 0", through the coilB, and out by the post D, or in the reverse direction. In passing alongthe parts of its circuit Oand (1 which are parallel to the arms a a ittends to deflect them, and so to turn the spindle A partly round withmore or less force, according as the current is greater orless. As shownin Figs. 4, 5, and 6, the electric current entering by the post 0 passesthrough a number of convolutions of fineinsulated wire, C C O 0*, woundround a rectangular casing, E, outside the spindle A and its coil B. Inthis case also the current in the parts 0 and G of the rectangular coilis parallel to the arms a a, and tends to deflect them the more thegreater the electromotive force.

At the front end of the spindle A is fixed a light index-wire, F, whichmay be of aluminium. It is counterbalanced by an adjustable weight, F,and is bent forward so as to project through a hole in a dial, G.Through this dial passes a central spindle, H, which can be turned byhand, and which has fixed to its inner end the innermost convolution ofa volute spring, K, the outermost convolution of which is connected byan arm, Is, to the index-wire F.

On the spindle H, outside the dial G, and protected bya glass, L, thereis fixed an index, M, pointing to graduations on the dial. WVhen theinstrument is put in circuit, the spindle H is turned by hand until theforce of the volute spring K is made to balance the force tending toturn the spindle A by deflecting the arms a a, as can be seen byobserving the point of the wire F just vibrating within the hole of thedial through which it passes. The index M will then point to agraduation on the dial G, by which can be ascertained the number ofamperes in the current acting on the electro dynamometer or the numberof volts in that acting on the volt-meter.

As shown in Figs. 4 and 6, 'a key, N, pressed upward by a spring,can beused to put the voltmeter in circuit by pressing down this key by thefinger, and thereby bringing into contact two metallic springs, n n, bywhich the circuit of the instrument is closed.

No claim is herein made to features described in this application whichare claimed in another application, No. 176,931, filed September 12,1885. v

Having thus described the nature of my invention and the best means Iknow for carrying it out in practice, I claim' 1. In an electric meter,the combination of a spindle which is turned by hand, a springconnecting the spindle turned by hand with a magnetic spindle, and amagnetic spindle whereby in each operation the operator in turning thespindle turned by hand puts an' increasing tension upon the spring untilit balances the deflecting force of the current, as and for the purposesdescribed.

2. The combination of the spindle H, the spring K, connecting thespindle H to the magnetic spindle A, the magnetic spindle A, theindicator F, and the needle M, which turns volute spring K, connected bythe arm is to the index-wire, as and for the purposes described. Intestimony whereof I have signed my name to this specification, in thepresence of two sub scribing witnesses, this 4th day of February, A. D.1885.

JOHN SMITH RAVORTH.

Witnesses:

WM. S. ROGERS,

105 Oheync l Vulk, S. H. A. SIEMENS, 81 Kensington Garden Square, Bagswarm, London, W.

